Concrete anticorrosive coating is an important protective material in modern buildings and industrial facilities, which is used to extend the service life of concrete structures and their internal steel bars and prevent corrosion damage. This article introduces several main types of concrete anticorrosive coatings in detail, including their composition, formulation, preparation method, construction process and practical application effect.
Epoxy modified styrene acrylic-polyvinyl acetate coating
This coating is made by combining epoxy resin-modified styrene acrylic emulsion with polyvinyl acetate, and is mainly used as a protective coating on concrete surfaces. Its composite emulsion formulation consists of 10% epoxy, up to 40% polyvinyl acetate and 50% styrene acrylic. The supporting coating components include mica iron oxide, zinc phosphate, fly ash and other pigments and fillers, which play a role in enhancing the compactness and anti-corrosion performance of the coating in the coating.
In the preparation process, the water and dispersant solution are first added to the mixing tank, and the pigments and fillers are added sequentially to disperse at high speed for 0.5 to 1 hour, and then the slurry is ground to the fineness through a ball mill, and then mixed and stirred with the compound emulsion and additives, and finally the defoamer is added to remove the foam and then put into a barrel. The coating forms a dense protective film on the surface of concrete, and when the thickness of the two coatings is greater than 10mm, its anti-rust performance reaches more than 9 levels, and is widely used in anti-carbonization and anti-corrosion projects of concrete buildings.
Moisture-curing epoxy coatings
Moisture-curing epoxy coatings are designed for concrete or steel structures in wet environments, and their unique moisture-curing properties allow them to form a uniform and dense protective film even on wet surfaces. The coating is divided into two components, A and B, the first component is composed of epoxy resin E44, talc, mica iron oxide, etc., and the B component contains a mixed curing agent, active additives and solvents. The two components are mixed in a 3:1 mass ratio.
When preparing, the epoxy resin is first dissolved in a mixed solvent, and other materials of component A are added in turn and ground to make a slurry. Component B is prepared by dissolving the curing agent in a solvent and adding additives to stir. After the A and B components are mixed, they are sprayed twice by a sprayer with a total dry film thickness of 260 microns. The coating has been tested for a long time in a wharf in Guangdong, and after 3 years, its coating is still smooth and dense, without discoloration and cracking, indicating that its performance is suitable for high humidity environments such as splash areas.
Epoxy powder coating
Epoxy powder coating is a high-performance coating for anti-corrosion of steel bars, and its formulation is mainly composed of solid epoxy resin, amine curing agent, polyester, leveling agent and filler. The preparation process involves coarse grinding of epoxy resin, mixing it with other components, extruding it through an extruder, cooling and crushing to the desired fineness, and drying and storage.
During construction, the surface of the steel bar is sandblasted or pickled to the Swedish standard SIS2.5, then preheated to 150 to 200°C and coated with a powder coating using high-pressure electrostatic spraying. Cures at 150 to 200°C for 10 to 30 minutes, cools and checks the coating quality. Coating defects can be repaired with liquid epoxy coatings. Epoxy powder coating has the advantages of dense coating, high hardness and superior corrosion resistance, and is widely used in bridges, building steel protection and other fields.
Olefin-based asphalt coatings
Olefin-based asphalt coatings are made by mixing olefin-based latex with pigment fillers, and their A components include 80% olefin-based latex, 5.5% additives, 9.5% pigment and filler, and 5% distilled water. It can be used after mixing with the asphalt silicate preservative of component B according to the mass ratio of 1:2.
This coating can be dried in 24 hours at room temperature, and can be dried in 30 minutes if heated to no less than 60°C, which is suitable for rapid corrosion protection of concrete structures. It is simple to apply and has excellent waterproof properties and durability after curing.
Epoxy anticorrosive coatings
Epoxy resin anticorrosive coating uses epoxy resin E20 and E44 as the main film-forming substances, with zinc powder, glass phosphorus sheet, graphite and other pigments and fillers, and uses a mixed solvent of butanol and xylene for dilution. When preparing, epoxy resin is ground and mixed with fillers and additives to form component A, and component B curing agent can be added and stirred evenly when used.
The coating forms a coating on the surface of concrete with excellent adhesion and corrosion resistance, and is resistant to salt spray, saturated calcium hydroxide solutions, and applied voltage. It has good flexibility after curing and can be widely used in industrial construction and anti-corrosion projects.
Concrete chimney anticorrosive coatings
Concrete chimney anticorrosive coatings are mainly used for the protection of the inner wall of industrial chimneys. Its A component is composed of adhesives, diluents and additives, and B component contains industrial waste residue, reinforcing materials and curing regulators, which are mixed in a ratio of 1:(0.9~1) and constructed.
The construction requirements are strict, and the base concrete needs to be strong enough, free of floating ash and with a moisture content of less than 8%. When painting, the first layer needs to be combined with a brown brush and an iron scraper to plug the pores and enhance the adhesion of the coating, and the thickness of each subsequent coating is about 1mm, and the total thickness is controlled within 3mm. After 10 to 14 days of curing, the coating can meet the requirements of anti-corrosion, suitable for high temperature, chemical corrosion environment.
summary
There are a wide range of anticorrosive coatings for concrete, ranging from epoxy modified emulsions to high-performance powder coatings. Different coatings have their own performance characteristics and application scenarios, such as moisture-curing epoxy coatings for wet environments, epoxy powder coatings for rebar protection, and chimney coatings for high temperature and chemical resistance. In practical application, only by selecting the appropriate coating according to the construction environment and specific needs, and strictly following the construction process, can we give full play to its protective effect and prolong the service life of the concrete structure.
